The state in 2008 began tracking “serious reportable events,” including operations performed on the wrong patient or the wrong body part, or surgical tools left inside a patient. Based on a Globe review of data, including projected numbers for the end of the year, hospitals were expected to report 94 errors for 2012, an increase of 65 percent over the previous year.

Hospitals themselves report such errors to the Department of Public Health, and it is possible that they are more regularly reporting these events when they occur, as they grow accustomed to what the law requires. And many of those reported last year are of a less serious nature. Still, these are considered “never events”—clearly preventable with at least the potential to cause harm to patients.

Some hospitals, including Boston Children’s and South Shore in Weymouth, did not report any surgical errors during 2011 and the first half of 2012, but nearly half of all facilities documented at least one.

The largest hospitals, including Massachusetts General and Brigham and Women’s, which do the most procedures, tended to report the greatest number of mistakes, many of them occurring outside their operating rooms. The Brigham reported 14 surgical errors during the 18-month period, 10 of them objects left inside patients, and 4 procedures on wrong body parts, including one case in which anesthesia was injected into the wrong leg of a patient. None of the patients suffered long-lasting harm, said Janet Barnes, executive director of compliance at the Brigham.

Mass. General reported nine surgical errors, including one where a wire used to guide medical staff as they inserted tubing into a vein was forgotten. Dr. Elizabeth Mort, vice president of quality and safety at the hospital, said it was removed without harm to the patient.

The case of mistaken identity that caused staff to insert a catheter into the wrong patient occurred at Beth Israel Deaconess, another large Boston hospital. Sands said new policies clarify who is responsible for making sure that the next patient brought into an exam room matches the patient on the schedule. A language barrier contributed to the error, he said. The patient, Sands added, did not suffer long-term harm.